Benzotriazole and tolyltriazole mixture with tetrachloroethylene

ABSTRACT

Solutions of mixtures of benzotriazole and tolyltriazole in water and organic solvents such as benzene and tetrachloroethylene are disclosed. The aqueous solutions contain 40 to 98 percent by weight of benzotriazole and from 60 percent to 2 percent by weight of tolyltriazole, on a solid basis. The aqueous solutions may also contain sodium hydroxide, potassium hydroxide or another pH control agent, and may also contain isopropanol, ethylene glycol or another organic solubilizer that is soluble in water. Aqueous solutions according to the invention are useful as additives for cooling water because of the ability of both benzotriazole and tolyltriazole to inhibit metal corrosion. The benzene solutions contain 2 to 98 percent by weight of benzotriazole and from 98 percent to 2 percent by weight of tolyltriazole, on a solids basis. The tetrachloroethylene solutions contain 2 to 98 percent by weight of benzotriazole and from 98 to 2 percent by weight of tolyltriazole, on a solids basis. Benzene benzotriazole/tolyltriazole solutions are useful in unleaded gasolines, and tetrachloroethylene - benzotriazole/tolyltriazole solutions are useful as dry-cleaning or metal-cleaning additives. Benzotriazole/tolyltriazole impregnated paper for use as a vapor phase corrosion inhibitor for copper and copper alloys may be produced without the use of a solvent system.

Korpics [4 1 June3,1975

Charles J. Korpics, Toledo, Ohio [73] Assignee: The Sherwin-WilliamsCompany,

Cleveland, Ohio 22 Filed: Mar. 9, 1973 211 Appl. 310.; 339,527

Related US. Application Data [63] Continuation of Ser. No. 152,528, June14, 1971,

Pat. No. 3,803,049.

[75] Inventor:

[52] 11.5. C1. 252/172; 2l/2.7 R; 252/8.55 E; 252/153; 252/171; 252/180;252/390; 252/394 [51} Int. Cl. ..C11d 7/50; C23f 11/14; C23g 5/02 [58]Field of Search 252/153, 390, 394, 180, 252/855 E, 170, 171, 172;260/308 B;

Primary Examiner-Benjamin R. Padgett Assistant Examinerlrwin GluckAttorney, Agent, or FirmOwen & Owen 57 ABSTRACT Solutions of mixtures ofbenzotriazole and tolyltriazole in water and organic solvents such asbenzene and tetrachloroethylene are disclosed. The aqueous solutionscontain 40 to 98 percent by weight of benzotriazole and from 60 percentto 2 percent by weight of tolyltriazole, on a solid basis. The aqueoussolutions may also contain sodium hydroxide, potassium hydroxide oranother pH control agent, and may also contain isopropanol, ethyleneglycol or another organic solubilizer that is soluble in water. Aqueoussolutions according to the invention are useful as additives for coolingwater because of the ability of both benzotriazole and tolyltriazole toinhibit metal corrosion. The benzene solutions contain 2 to 98 percentby weight of benzotriazole and from 98 percent to 2 percent by weight oftolyltriazole, on a solids basis. The tetrachloroethylene solutionscontain 2 to 98 percent by weight of benzotriazole and from 98 to 2percent by weight of tolyltriazole, on a solids basis. Benzenebenzotriazole/tolyltriazole solutions are useful in unleaded gasolines,and tetrachloroethylene benzotriazole/- tolyltriazole solutions areuseful as dry-cleaning or metal-cleaning additives.Benzotriazoleltolyltriazole impregnated paper for use as a vapor phasecorrosion inhibitor for copper and copper alloys may be produced withoutthe use of a solvent system.

1 Claim, 7 Drawing Figures CURVE A CURVEB NCIZIXTURES SPEIT R S BIL] V FTT I IE l TNTW'TJTIIKET'IE new 3887'481 SHEET 3 TRIAZOLE CONTENT 10%BT/TT RATIO =bO/I20. b ALKALI USED SN-KOH.

PER CENT ISOPRO PANOL PH 0! A IO'A TRIAZOLE MIXTURE IN JSOPROPANOL-H OMIXTURE.

FIE-4- BENZOTRIAZOLE AND TOLYLTRIAZOLE MIXTURE WITHTETRACI-ILOROETHYLENE This is a continuation of Application Ser. No.152,528, IFiled June 14, 1971, now U.S. Pat. No. 3,803,049.

DEFINITIONS The abbreviation ET is used herein to refer to benzotriazolell l N The abbreviation TT is used herein to identify tolyltriazole tisomer mixtures) BACKGROUND OF THE INVENTION Cooling water is used inmany industrial, commercial and even private systems in connection withair conditioning and other temperature-control systems and to removeheat from various commercial processes, e.g. in connection withfractional distillations and various chemical processes. To the actualuser of cooling water, the source may be his local water system, anearby river, lake or stream, or a spring or well. Numerous difficultiesmay be encountered in using cooling water, depending upon whatimpurities are in the water from the particular source selected. Forexample, if the cooling water is vaporized, scale formation may be aproblem, this problem can be avoided by softening the water, e.g., byion exchange treatment or by precipitating the scale formers, by addinga sequestering agent such as a lignosulfonate, an inorganicpolyphosphonate, an organo phosphonate or a polysilicate of the typeformed by a sodium silicate, or, as suggested in US. Pat. No. 3,492,240,by adding hydrolyzed polyacrylonitrile or, as suggested by French Patent1,550,452, by adding polymethacrylic acid or an alkali salt thereof. Itis frequently desirable to add a biocide to cooling water, e.g., toinhibit the growth of algae therein. Frequently, cooling water iscirculated in a system made of at least one metal, so that inhibitingcorrosion of the metal by the water is desirable. It has been suggested,South African Patent 68/03379, that a combination of an organophosphonicacid, a water soluble azole and a water soluble zinc salt can be used toprevent corrosion (see also, US. Pat. No. 2,941,953). Water solublecorrosion inhibitors added to the water form a monomolecular film at themetal-water interface. Compounds suggested are: inorganicpolyphosphates, inorganic polyphosphates plus zinc, chromate-zinc andchromate-zinc-phosphate. Nonchromate compounds includeamino-methylene-phosphonate (AMP) plus zinc, polyol-ester phosphate withor without zinc and polyacrylamide-silica polymers. See Cooling TowersBoost Water Reuse Environmental Science & Technology, Volume 5, No. 3 p.205 (March 1971). Water from the available source may also contain silt,which can cause serious loss of heat exchange efficiency unless itsdeposition on heat exchanger surfaces is prevented. This can beaccomplished by using certain lignosulfonate dispersants or, preferably,polyelectrolytes, in particular polyacrylics: see, for example GeneralDeposit Control Mechanisms, William H. Hales, Special Report presentedat: International Water Conference, 13th Annual Meeting, William PennHotel Pittsburgh, Pennsylvania, October 2'830, 1969.

The treatment of the water in cooling water systems is a continuingproblem, because chemicals added to the system may be lost as aconsequence of chemical reactions that are involved in their performanceof the desired function, because the chemical composition of the coolingwater is changed as a consequence of its actual use, because make-upwater must be added to the system from time to time, thereby dilutingthe entire system, because cooling water is periodically or continuallyremoved from the system to prevent salt buildup, or for a combination ofthese and other reasons. Accordingly, it is necessary to monitor anygiven cooling water system periodically, and to make appropriateadditions of treating chemicals. The frequency of the monitoring andaddition varies drastically from system to system, and may be measuredin months, weeks, days or hours: in extreme cases, continuous monitoringmay be required.

It is highly desirable to add various treating chemicals to coolingwater as aqueous solutions, because this enables volumetric metering asdistinguished from gravimetric metering. It is much easier to add therequired number of milliliters of a solution of known concentration thanit is to add the corresponding number of milligrams of a solid treatingchemical. Triazoles that can be used effectively to treat cooling water,e.g., BT and TT have comparatively low water solubilities of slightlyless than 2 grams in grams of water and slightly less than /2 gram in100 grams of water, respectively. It would be desirable to use TT as thewater-soluble triazole, because ET is the more expensive of the two.However, the higher water-solubility of BT makes it preferable, althougheven the higher water solubility of ET is sufficiently low to militateagainst its addition, in most instances, to cooling waters in the formof a water solution. Accordingly there is a need for a shippablesolution, preferably containing TT, having a sufficiently high triazoleconcentration that it can be used to add triazole to cooling watersystems.

Triazoles, including BT and TT, are also useful in the dry-cleaning andmetal-cleaning industries. Drycleaning solvents such as chlorinatedhydrocarbons and petroleum naphthas commonly use amine, phosphate orsulphonate-based detergents. These detergents have been found to causecorrosion of metal machine parts, especially copper. US. Pat. No.3,337,47l suggests the use of BT and TT compounds added to the drycleaning solvent to prevent attack by the corrosivedetergent-solvent-moisture combination.

A further use for triazoles is suggested by British Patents Nos. 907,794and 954,564 which disclose that copper and copper-base alloys may beprotected against discoloration by impregnating packaging materials withan aqueous or organic solution of a benzotriazole.

SUMMARY OF INVENTION The instant invention is based upon the discoverythat the solubility of certain blends of BT and TT in water and organicsolvents is higher than would be expected on the basis of the water andorganic solubilities of the two components of the blends. Specifically,aqueous blends of from 40 percent (The terms per cent and parts" areused herein, and in the appended claims, to refer to percent and partsby weight, unless otherwise indicated.) to 98 percent of BT with from 60percent to 2 percent of TT have unexpectedly high solubility. Benzeneblends of from 2 percent to 98 percent of BT with from 98 percent to 2percent ofTT have un' expectedly high solubility. Tetrachloroethyleneblends of from 2 percent to 98 percent of BT with from 98 per cent to 2percent of TT have unexpectedly high solubility.

In another aspect, the invention is based upon the discovery that thesolubility of BT, TT and blends of the two in water can be substantiallyenhanced by partially neutralizing the acid function of the triazole,for example with sodium hydroxide or potassium hydroxide. The inventionis based upon the further discovery that the water solubility of BT, ofTT, and of blends of the two can be still further enhanced by use of alimited amount of a water miscible organic solvent such as isopropanolor ethylene glycol in the solution.

In yet another aspect, the invention is based upon the discovery that aBT/TT mixture may be used to impregnate paper for use as a vapor phasecorrosion inhibitor for copper and copper alloys without the use of asol vent system.

OBJECTS It is, therefore, an object of the invention to providerelatively concentrated solutions of BT, of TT, or of mixtures of thetwo.

It is a further object of the invention to provide an aqueous solutionof a blend of from 40 percent to 98 percent of BT with from 60 percentto 2 percent of TT, on a solids basis, and having an unexpectedly hightriazole content.

It is another object of the invention to provide a solution of BT, TT,or a blend of BT and TT that is unexpectedly concentrated as aconsequence of the partial neutralization of the acid function of thetriazole.

It is a still further object of the invention to provide It is a stillfurther object of this invention to provide a tetrachloroethylenemixture of a blend of 2 percent to 98 percent BT with from 98 to 2percent of TT, on a solids basis, and having an unexpectedly hightriazole content.

It is a still further object of the invention to provide a method forimpregnating paper products with a BT/TT mixture for use as a vaporphase corrosion inhibitor for copper and copper alloys without thenecessity of a solvent system.

Other objects and advantages will be apparent from the description whichfollows, reference being made to the accompanying drawings, in which:

DESCRIPTION OF DRAWINGS FIG. 1 is a graph showing water solubility, ingrams per 100 grams of water, of BT, TT and mixtures of BT and TT at25(All temperatures reported herein are in degree Centigrade, unlessotherwise indicated.)

FIG. 2 is a graph showing the minimum pH at which a 10 percent solutionof BT, of TT, or of mixtures of BT and TT containing 10 percent of thetriazole or triazole composition can be achieved in water containing 10percent of isopropanol.

FIG. 3 is a graph showing the minimum pH at which a 10 percent triazolecontent can be achieved, using a combination of parts of BT and 20 partsof TT in water and in various combinations of water and ethylene glycol.

FIG. 4 is a graph similar to FIG. 3, but showing the minimum pH at which10 percent triazole content can be achieved, using a mixture of 80 partsof BT and 20 parts of TT, in water and in various mixtures of water andisopropanol.

FIG. 5 is a graph showing benzene solubility in grams/ ml. of benzene,of BT, TT and mixtures of BT and TT at 25.

FIG. 6 is a graph showing tetrachloroethylene solubility in grams/I00ml. of tetrachloroethylene, of BT, TT and mixtures of BT and TT at 25.

FIG. 7 is a graph showing the melting point range of BT/TT mixtures.

EXAMPLE I The solubilities of BT and TT in water at 25 were de terminedfrom solutions in equilibrium with a solid at 25.

The solubilities of BT and TT mixtures were determined by addingincrementally differing amounts of each mixture to known amounts ofwater and rotating each such combination of BT, TT and water in a closedvessel immersed in a constant temperature bath maintained at 25. Suchrotation was continued for 16 hours, and the solution containing thehighest concentration of completely dissolved solids was taken as thewater solubility of each such mixture. The results of this investigationare presented in graphic form in FIG. 1 of the attached drawings. Twocurves are shown in FIG. 1; Curve A shows experimentally determinedsolubilities of BT/TT mixtures, and Curve B shows theoretical maximumsolubilities calculated from the solubility in water of BT and TT alone.

In an ideal solution there is complete uniformity of cohesive forces,i.e., if there are two components A and B, in solvent C, the forcesbetween A and B, A and A, and B and B are all the same. In such asolution, the maximum amount of A and B capable of being dissolved inSolvent C will be equal to the sum of the solubility of each componentalone in the given solvent. Because forces between components in asolvent are not equal, the actual solubility of a mixture is usuallymuch less than the predicted solubility.

As indicated in FIG. 1, the curves of the experimentally determinedsolubility values and the theoretical maximum solubility values of BT/TTmixtures in water are similar. The experimentally determined solubilityof the BT/TT mixtures is unexpectedly higher than the theoreticalmaximum solubility, on the basis of the water solubility of BT and TTalone, for mixtures containing from 40 percent to 98 percent BT, withfrom 60 percent to 2 percent, of TT. Such solutions are, therefore,unexpectedly useful as additives for cooling water treatment. Theunexpected increase in the total amount of BT/TT mixture dissolved at agiven BT/TT ratio is indicated by the shaded area between the twocurves.

Preliminary experimental NMR isomer ratio data indicate that theisomeric mixture of tolytriazole contains approximately 40 percent4-Methylbenzotriazole and 60 percent Methylbenzotriazole. By changingthe proportion of isomers present in the BT/TT mixture, the maximumsolubility of the BT/TT mixture might be increased or decreased.

WATER SOLUBILITY OF MIXTURES OF BT/I'I' AT 25C.

The calculations for theoretical maximum solubilities of varying BT/TTratios were based on the experimentally determined solubility of BT andTT, alone, in the solvent used. As listed in the table above, and shownin FIG. 1, the solubility of TT in water is 0.450 g/lOO ml. H 0, and thesolubility of ET is 2.00 g/l00 ml. H O. The maximum theoreticalsolubility of a BT/TT mixture is the sum of the BT and TT solubilities,alone; 2.450 g/lOO ml. H O. To calculate the maximum theoreticalsolubility of, for example, a 60/40 TT/BT mixture, 60 percent ofX 0.450g. TT/l00 ml. H O where X Total BT/TT mixture theoretically capable ofbeing dissolved. Therefore, for a 60/40 TT/BT mixture, X 0.750 g. TT/BT.Similar calculations may be used to determine the theoretical maximumsolubility of other BT/TT mixtures, in other solvents.

EXAMPLE 2 A 10 gram portion ofa mixture of 80 parts of BT with parts ofTT was suspended in 90 grams water and a 5 normal NaOH solution in waterwas added dropwise, with stirring until all solids were in solution. Itwas determined that the amount of sodium hydroxide required to causesolution was approximately 30 percent of that theoretically required toneutralize the acid function of the triazole composition; the pH of thesolution was 8.3.

EXAMPLE 3 Several procedures similar to that described above in Example2 were carried out, except that BT, TT and mixtures of BT and TT, 10grams each, were added to 90 grams of water containing 10 percent ofisopropanol, and 5 normal KOH was added dropwise to each suchcomposition until all of the solids dissolved. The results of theseprocedures are presented graphically in FIG. 2 of the attached drawings,which shows that (a) for 100 percent BT, sufficient 5 normal potassiumhydroxide was required for dissolution to raise the pH to about 7.7; (b)for an /20 blend of BT and TT, sufficient potassium hydroxide to raisethe pH to about 7.75 was required; (0) for a 50/50 blend of BT and TT,sufficient potassium hydroxide to raise the pH to about 8.1 wasrequired; and (d) for TT, sufficient potassium hydroxide to raise the pHto about 8.8 was required.

EXAMPLE 4 Several procedures similar to those described in Example 3were conducted, except that 10 gram portions of an 80/20 mixture of BTand TT were dissolved in grams of water, or of water containing variousamounts of added ethylene glycol. Five normal potassium hydroxide wasthen added dropwise to each composition until all solids dissolved. FIG.3 shows the pH at which all solids were dissolved as a function of thepercent of ethylene glycol added to the water.

EXAMPLE 5 Several procedures similar to those described in Example 4were carried out, except that 10 gram portions of an 80/20, BT/TTcomposition were dissolved in 90 grams of water or in 90 grams of waterto which varying amounts of isopropanol has been added. FIG. 4 shows thepH at which complete solution was achieved as a function of the percentof isopropanol in the water.

EXAMPLE 6 The solubilities of BT, TT and mixtures in benzene at 25 weredetermined at 25. A modified experimental procedure similar to thatdescribed in Example 1 was used, except benzene was substituted forwater as the solvent. Because of the differing solubilities of BT andTT, a number of solutions containing incrementally differing amounts ofa given mixture were rotated for at least 16 hours in a constanttemperature bath. The results are presented for clarity on asemi-logarithmic scale as shown in FIG. 5. Two curves are shown; Curve Ashows experimentally determined solubilities of BT/TT mixtures, andCurve B shows theoretical maximum solubilities calculated from thesolubility in benzene of BT and TT alone. The theoretical maximumsolubility for an ideal solution would be 1.6 g./l00 ml. benzene for a50/50 BT/TT mixture. The experimentally determined maximum solubilityshows a greater than -fold increase over the theoretical maximumsolubility.

FIG. 5 shows that the benzene solubility is unexpectedly high, on thebasis of benzene solubility of BT and TT alone, for mixtures containingfrom 2 percent to 98 percent or even more BT, with from 98 percent to 2percent, or even less, of TT. The unexpected increase in the totalamount of BT/TT mixture dissolved at a given BT/T'Tratio is indicated bythe shaded area between the two curves. Unleaded gasolines typically/may7 contain from 40-60 percent benzene, toluene, or xylene as aromaticcompounds. The unexpectedly high solubility of BT/TT mixtures in benzenemakes such mixtures useful for use in unleaded gasoline to preventcorrosion of the fuel system.

BENZENE SOLUBILITY OF MIXTURES OF BT/TT AT 25C.

EXAMPLE 7 The solubilities of BT, TT and mixtures intetrachloroethylene' at 25 were determined at 25. The experimentalprocedure used was thatdescribed in'Example 6, excepttetrachloroethylene was substituted for benzeneas the solvent. Becauseof the differingsolubilities of BT and TT, a number of solutionscontainingincrementally differing amounts of a given mixture wererotated for at least 16 hours in'a'c'onstant temperaturebath. Theresults are presented for clarity on a semi logarithmic scale as shownin FIG. 6. Two curves are shown; Curve A shows experimentally determinedsolubilities of BT/TT mixtures, and Curve B shows theoretical maximumsolubilities calculated from the solubility in tetrachloroethylene of BTand TT alone. The theoretical maximum solubility for an ideal solutionwould be 0.25 g./l ml. tetrachloroethylene for a 50/50 BT/TT mixture.The experimentally determined maximum solubility shows a greater thansix-fold increase over the theoretical maximum solubility. Theunexpected increase in the total amount of BT/TT mixture dissolved at agiven BT/TT ratio is indicated by the shaded area between the twocurves. The tetrachloroethylene solubility is unexpectedly high, on thebasis of tetrachloroethylene solubility of BT and TT alone, for mixturescontaining from 2 percent to 98 percent or even more BT, with from 98percent to 2 percent, or even less, of TT. Such solutions are,therefore, unexpectedly useful as additives in the dry-cleaning ormetal-cleaning industry.

TETRACHLOROETHYLENE SOLUBlLlTY OF MIXTURES OF BT/l'l' AT C.

7 Theoretical TT/BT Ex erimental Maximum Ratio So ubility Solubility0/100 0.10 g/l00 ml, tetrachloro 0.10

ethylene 10/90 0.18 0.11 20/80 0.30, 0.124 7 /70 0.40 0.143 40/60 0.680.166 50/50 1.35 0.200 60/40 1.58 0.250 70/30 0.60 0.214. 80/20 0.400.187 90/10 0.30 0.165 100/0 0.15 0.150

EXAMPLE 8 The melting point profile of a series of BT/TT mixtures wasexperimentally determined by standard pro- I cedures. As showngraphically in FIG. 7, a'series of melting point of 73. Becauseof thelow melting point BT/TT mixtures, in 10 percent increments, was used todetermine the eutectic point. The experimental results show that while a100/0 mixture of BT/TT has a melting point of about 98", a 50/50 BT/TTmixture has a of the BT/TT mixture, paper can be impregnated therewithby spraying or brushing the molten mixture onto the paper, thus,eliminating the need for the, use, of a solvent system to accomplishsuch impregnation. This is important, because the cost of solventrecovery or, in

theabsenceof Solventrecovery, the cost of'the solvent is eliminated. Itis also known that incomplete solvent.

recovery contributes to environmental pollution. Paper impregnated'withBT. and TT'is useful because it acts I as a vapor phase corrosioninhibitor for copper and copper alloys wrapped therein. Although theBT/TT mixture does not recrystallize readily, paper impregnatedtherewith was not tacky; the BT/TT mixture did not stain the metalsamples tested.

The unexpected increase in maximum solubility of BT/TT mixtures in suchdiverse solvents as benzene and tetrachloroethylene, as demonstrated inExamples 6 and 7, indicates that increased solubility in such aromaticsolvents as toluene, xylene, ethylmethylbenzene, propyl orbutyl-benzene, and aliphatic solvents such as methylene chloride andmixtures, may be expected.

What I claim is:

11. A solution of a triazole in tetrachloroethylene, consisting of amixture of from 2 to 98 percent of henzotriazole and from 98 to 2percent of tolyltriazole, where the total amount of triazole dissolvedis a func tion of the proportion of benzotriazole and tolyltriazolepresent in the solution, and is represented by the shaded area betweencurve A and B of FIG. 6 of the at-

1. A SOLUTION OF A TRIAZOLE IN TETRACHLOROETHYLENE, CONSISTING OF A MIXTURE OF FROM 2 TO 98 PERCENT OF BENZOTRIAZOLE AND FROM 98 TO 2 PERCENT OF TOLYTRIAZOLE, WHERE THE TOTAL AMOUNT OF TRIAZOLE DISSOLVED IS A FUNCTION OF THE PROPORTION OF BENZOTRIAZOLE AND TOLYLTRIAZOLE PRESENT IN THE SOLUTION, AND IS REPRESENTED BY THE SHADED AREA BETWEEN CURVE A AND B OF FIG. 6 OF THE ATTACHED DRAWING. 